C# (pronounced “C Sharp”) is a modern, object-oriented, and type-safe programming language developed by Microsoft. It is widely used for developing desktop applications, web services, and mobile apps. C# supports multiple programming paradigms, including imperative, declarative, functional, generic, object-oriented, and component-oriented programming.
Few things I like about C# are
- It’s a simple and easy to learn language.
- The extensive standard library and ecosystem, including ASP.NET and .NET Core.
Few things I dislike about C# are
- The language has nullable reference types.
- It rely on dotnet runtime.
- I’m not a big fan of object-oriented programming.
Variables
Variables in C# are used to store data which can be manipulated by the program. Here’s how you declare variables:
Syntax and Example:
// Variable declaration
int myNumber = 10;
string myString = "Hello, World!";
bool myBool = true;
// Constant declaration
const double PI = 3.14159;
// Type inference using var
var myVar = "This is inferred as a string";
Control Statements
Control statements in C# direct the flow of the program execution based on conditions. Common control statements include if, switch, for, foreach, while, and do-while.
Syntax and Example:
// If statement
if (x > 0)
{
Console.WriteLine("x is positive");
}
// For loop
for (int i = 0; i < 10; i++)
{
Console.WriteLine(i);
}
// foreach loop
string[] days = {"Monday", "Tuesday", "Wednesday"};
foreach (string day in days)
{
Console.WriteLine(day);
}
// While loop
while (x > 0)
{
Console.WriteLine(x);
x--;
}
// Switch statement
switch (day)
{
case "Monday":
Console.WriteLine("It's Monday!");
break;
case "Tuesday":
Console.WriteLine("It's Tuesday!");
break;
default:
Console.WriteLine("It's not Monday or Tuesday");
break;
}
Functions
Functions in C# are blocks of code that perform a specific task and can be called from other points in a program.
Syntax and Example:
// Function declaration
public int Add(int a, int b)
{
return a + b;
}
// Function call
int result = Add(5, 3);
Console.WriteLine(result);
// Anonymous functions
Func<int, int, int> add = (x, y) => x + y;
// Function with multiple return values
public (int, int) GetMinMax(int[] numbers)
{
int min = numbers.Min();
int max = numbers.Max();
return (min, max);
}
var (min, max) = GetMinMax(new int[] {1, 2, 3, 4, 5});
Data Structures (Classes)
Classes in C# are data structures that can contain data members (fields and properties) and function members (methods, constructors).
Syntax and Example:
public class Person
{
public string Name { get; set; }
public int Age { get; set; }
public Person(string name, int age)
{
Name = name;
Age = age;
}
public void SayHello()
{
Console.WriteLine("Hello, my name is " + Name);
}
}
// Creating an instance of a class
Person person = new Person("Alice", 30);
// Accessing fields and methods
Console.WriteLine(person.Name);
person.SayHello();
In C# the classes define an object with values and methods. The object is an instance of the class.
Interfaces
Interfaces in C# define a contract that classes can implement, specifying a set of methods that the implementing type must contain.
Syntax and Example:
public interface IShape
{
double Area();
double Perimeter();
}
// Implementing the interface
public class Circle : IShape
{
public double Radius { get; set; }
public double Area()
{
return Math.PI * Radius * Radius;
}
public double Perimeter()
{
return 2 * Math.PI * Radius;
}
}
Collection Manipulation
C# provides a variety of collection types, such as arrays, lists, dictionaries.
Syntax and Example:
// Array
int[] numbers = {1, 2, 3, 4, 5};
// List
List<int> numbers = new List<int> {1, 2, 3, 4, 5};
// Iterating through a list
foreach (int number in numbers)
{
Console.WriteLine(number);
}
// Adding to a list
numbers.Add(6);
// Removing from a list
numbers.Remove(3);
// Dictionary
Dictionary<string, int> ages = new Dictionary<string, int>
{
{"Alice", 25},
{"Bob", 30}
};
// Accessing dictionary values
Console.WriteLine(ages["Alice"]);
// Iterating through a dictionary
foreach (var pair in ages)
{
Console.WriteLine(pair.Key + " is " + pair.Value + " years old");
}
// Adding to a dictionary
ages["Charlie"] = 35;
// Removing from a dictionary
ages.Remove("Bob");
Linq (Language Integrated Query)
LINQ is a set of features that extends powerful query capabilities to the C# language, allowing you to easily retrieve data from arrays, XML, databases, and more with a SQL-like syntax.
Syntax and Example:
int[] numbers = {1, 2, 3, 4, 5};
var evenNumbers = from number in numbers
where number % 2 == 0
select number;
Error Handling
Error handling in C# is accomplished using try-catch blocks, allowing you to catch exceptions that occur during program execution.
Syntax and Example:
// throwing an exception
public void DoSomething()
{
throw new Exception("Something went wrong");
}
// catching an exception
try
{
DoSomething();
}
catch (Exception e)
{
Console.WriteLine("Error: " + e.Message);
}
finally
{
Console.WriteLine("Finished execution");
}
Concurrency
C# supports concurrent programming primarily through the System.Threading and System.Threading.Tasks namespaces, enabling multi-threading and asynchronous programming.
Syntax and Example:
using System.Threading.Tasks;
public class Example
{
public static async Task DoWorkAsync()
{
await Task.Run(() =>
{
// Simulate long-running task
Thread.Sleep(1000);
Console.WriteLine("Work completed");
});
}
// Using Task.WaitAll()
public static void Main()
{
Task t1 = DoWorkAsync();
Task t2 = DoWorkAsync();
Task.WaitAll(t1, t2);
}
}
Ecosystem
Installation
.NET can be installed from the official .NET download page or using package managers like Homebrew on macOS.
brew install --cask dotnet
Hello World
using System;
namespace HelloWorld
{
class Program
{
static void Main(string[] args)
{
Console.WriteLine("Hello, World!");
}
}
}
CLI
dotnet new console -n <project-name>: Create a new console projectdotnet run: Build and run the .NET projectdotnet build: Build a .NET projectdotnet build --runtime ubuntu.20.04-x64for Linuxdotnet build --runtime win10-x64for Windowsdotnet build --runtime osx.10.15-x64for macOS
dotnet test: Run tests in the projectdotnet fmt: Format the code (requires installing a tool likedotnet-format)dotnet add package <package-name>: Add a NuGet package to the project
Package Management
NuGet is the package manager for .NET. It is integrated into the .NET CLI with commands like:
dotnet add package <package-name>- Add a NuGet package to the projectdotnet remove package <package-name>- Remove a NuGet package from the projectdotnet restore- Restore the dependencies and tools of a project
Popular Libraries
- ASP.NET Core - Open-source framework for web apps and services
- Entity Framework Core - Modern object-database mapper for .NET
- xUnit - Testing framework for .NET
- Serilog - Diagnostic logging library for .NET applications
- Automapper - A convention-based object-object mapper
- MediatR - Simple, unambitious mediator implementation in .NET
Special Features
- LINQ (Language Integrated Query): A set of features that extends powerful query capabilities to the C# language, allowing you to easily retrieve data from arrays, XML, databases, and more with a SQL-like syntax.
- Async/Await: Simplifies asynchronous programming, allowing you to write asynchronous code that is as straightforward as synchronous code without complex callbacks or manual thread management.